1. Field of the Invention
The present invention relates to a drive device, an LED array, an LED head, and an image forming apparatus provided therewith.
2. Description of Related Art
Conventionally, an electrophotographic image forming apparatus such as a printer is provided with an exposure head having a plurality of pairs of light-emitting element array chips and corresponding drive devices, the light-emitting element being manufactured by arranging a plurality of arrays of light-emitting elements such as an LED (Light Emitting Diode) or the like. Arrays of the light-emitting array chips and the drive devices are arranged in a direction perpendicular to a direction of array of drive elements to reduce the entire size of the exposure head.
This type of image forming apparatus is required to improve image quality in recent years, followed by high-density mounting of light-emitting elements and drive elements, leading to further narrowing of a pitch between electrode pads for the purpose of connection between the light-emitting elements and the drive elements. Japanese Unexamined Patent Application Publication Nos. 2001-138567 and H10-35011 disclose a light-emitting element array or a drive circuit such as described above.
To be more specific, drive circuits described in Japanese Unexamined Patent Application Publication No. 2001-138567 are structured such that drive devices are provided at one end with electrode pads for connecting the drive devices to light-emitting element arrays, and at the other end with electrode pads for a power source, control signals, and the like in order to provide intervals for wire bonding or the like.
Light-emitting element arrays described in Japanese Unexamined Patent Application Publication No. H10-35011 are structured to decrease the number of electrode pads by forming in a matrix form, wires for connecting drive circuits to an anode terminal side of or a cathode terminal side of light-emitting array chips. The light-emitting element arrays are also structured such that only a target light-emitting element is driven under control of each corresponding drive circuit.
The art described above accomplishes narrowing of a pitch between the electrode pads in a direction of arrays of the light-emitting elements but has problems in that downsizing cannot be achieved in a direction perpendicular to a direction of light-emitting element arrays and arrays of the drive devices, that is, perpendicular to a direction of arrays of the drive elements.
The present invention has been made in consideration of the above situation, and has as its object to achieve downsizing of a drive device, an LED array, an LED head, and an image apparatus provided therewith by achieving downsizing in a direction perpendicular to a direction of the of the light-emitting element arrays in the drive circuit as described above.